基于变形控制的凝灰岩隧道稳定性评判基准研究

Study on Stability Evaluation Criteria of Tuff Tunnel Based on Deformation Control

目的针对绍兴特定地区,建立隧道施工围岩稳定性评判指标及控制基准。方法采用数理统计方法,对已有的718个监测断面的拱顶沉降实测数据进行归纳总结,基于不同围岩等级及隧道埋深,从累积拱顶沉降与相对拱顶沉降两方面得到隧道围岩变形评判基准,然后考虑测前位移损失,通过数值模拟方法分析不同工法的拱顶沉降位移释放率,对评判基准结果进行修正。结果不同施工方法的拱顶沉降位移释放率从大到小依次为全断面法、台阶法、单侧壁导坑法;累积拱顶沉降相对于设计预留变形量偏小,设计较保守;相对拱顶沉降随埋深变化呈交错变化规律,相同围岩级别的相对拱顶沉降分布区间较集中,随着围岩级别变差,分布区间范围越大。结论提出绍兴地区凝灰岩隧道围岩变形评判基准双控指标及建议值,对后期类似地区隧道设计及施工具有重要指导意义。

According to the specific area of Shaoxing,the evaluation index and control standard of surrounding rock stability of tunnel construction are established.Using mathematical statistics method,the measured data of 718 monitoring sections of vault settlement are summarized.Based on different surrounding rock grades and tunnel buried depth,the evaluation criteria of tunnel surrounding rock deformation are obtained from cumulative vault settlement and relative vault settlement.Then,considering the displacement loss before measurement,the release rate of vault settlement displacement of different construction methods is analyzed by numerical simulation method,the benchmark results were revised.The release rate of vault settlement displacement of different construction methods from large to small is full section method,bench method and side heading method.The accumulated vault settlement is smaller than the design reserved deformation,and the design is conservative;The distribution range of relative vault settlement with the same surrounding rock grade is more concentrated,With the deterioration of surrounding rock grade,the distribution range is larger.This paper puts forward the double control index and recommended value of surrounding rock deformation evaluation standard of tuff tunnel in Shaoxing area,which has important guiding significance for later tunnel design and construction in similar areas.